The greatest criticism (from people within the mental health community) of the DSM is that the diagnostic criteria are normative...which is exactly what you are saying.
Does not fitting in, or not being like others, mean one is ill? Does not conforming to a societal expectation also mean that one might be ill? What is the standard?
Some outliers in the profession (Thomas Szasz, ex) would say that mental illness is a societal construct.
I don't know what's true. I think if someone is miserable and feeling like they can't cope, well then that person should get help. If someone is dangerous to others, well then that person needs to get some sort of attention (or maybe incarceration).
Mental illness is funny though. As you describe it here, it has to do with profitability and productivity. That doesn't cut it for me.
Interesting blog.